The present invention relates to an apparatus for the conveying of plastics material containers, in particular of plastics material pre-forms. A plurality of conveying apparatus for the conveying of plastics material containers is known from the prior art. In particular, conveying devices for the conveying of plastics material pre-forms are also known. Plastics material pre-forms of this type are usually first heated in the production process and after that are shaped into plastics material containers in a blow moulding machine such as for example a stretch blow moulding machine. For this purpose it is necessary for these plastics material pre-forms to be conveyed already sorted, for example to a single-stroke wheel. So-called roller-type sorting means, which have two rotating rollers which are arranged parallel to each other and between which the plastics material pre-forms are conveyed, are known from the prior art for this purpose.
An apparatus of this type is described for example in DE 601 18 772 T2. In this case an ejection apparatus is also provided, which permits an ejection of incorrectly orientated pre-forms from the conveying system.
U.S. Pat. No. 4,223,778 describes a further “pre-form” conveyor of the type described above. Here too in this case the rollers are also arranged at a distance from each other such that only the end portions of the pre-forms can fall into the gap formed by the rollers, but the carrier rings are held. As a result of a suitable inclination of these two rollers the plastics material pre-forms can be conveyed under the action of gravity.
The aforesaid rollers of roller-type sorting means of this type are usually metallic rollers which have to be balanced very precisely.
In recent years plastics material pre-forms with very small carrier rings have been processed to an increasing degree. This results to an increasing degree, however, in problems with the roller geometry in the roller-type sorting means. In this case the plastics material pre-forms slip increasingly deeply into the interspace formed between the two rollers and can no longer be correctly conveyed in part. In addition, jamming occurs increasingly frequently and the sliding behaviour also decreases.
The object of the present invention is therefore to improve roller-type sorting means in particular also for problematic plastics material pre-forms such as plastics material pre-forms with comparatively small carrier ring diameters.